By Cazoo1
Worcestershire,
United Kingdom 
Good Morning...In my garden I have a Myrtle bush....which is getting too large...at the moment it is in flower. I say in flower but they are so very sparse it hardly seems worth growing it at all. How far back can I prune it without killing it...and why do I only get such a poor show ??
I would blame the weather but it has been like this for years...such a shame as the fragrance from the flowers is lovely. Hope you guys can help me.....Thanks
15 Aug, 2022
Answers
It looks as if it has been trimmed at some time to keep it in check. I find that mine flowers on the growth which is oldest, not the newer growth. It can be thinned out a lot,
like hair, just leave pieces that you want to keep unpruned & if we get sunny weather again next year they will flower for you.
16 Aug, 2022
If in doubt then wait until its finished flowering and reduce by one third; which it looks like much of the new growth its put on this year. I would give it a good dose of potassium (potash) in the spring to encourage it to flower later on in the season.
15 Aug, 2022